Pyrazolone azo dyestuffs



'20 duction discharges. For this reason the dyestuifs Zene are taken for the parts of p-amihophehol 20 Patented Oct. 25, 1938 r 2,134,035

2,134,035 PYRAZOLONE AZO DYESTUFFS George Holland Ellis, Spondon, near Derby, England, assignor to Celanese Corporation of America, a corporation of Delaware No Drawing. Application January 6, 1936, Serial No. 57,767. In Great Britain January 9, 1930 4 Claims. (01. 260162) This application is a continuation-in-part of parts of water and 17 parts of hydrochloric acid U. S. application 8. No. 535,296 filed May 5th, (32%) and 30 parts of broken ice added. 3.6 1931, which is a continuation-in-part of U. S. apparts of sodium nitrite, dissolved in parts of plication S. No. 500,428 filed December 5th, 1930. Water are then added to effect diazotization. This 5 It relates to a new class of azo dyes, and to procdiazo solution is then run slowly into a solution 5 esses for the production of the same. of 9 parts of l-phenyl-3-methyl-5-pyrazolone in The new dyes of the invention contain a pyraz- 80 parts of water containing 2 parts of caustic olone residue linked through an azo group to an soda, alkalinity being maintained by addition of aromatic residue containing a hydroxy group in soda ash solution. When coupling is com- 10 the para position to the azo group. The pyrazplete the dyestufi is collected by filtration, washed 10 olone nucleus is preferably that of a l-phenyl-B- well, and retained suitably as an aqueous paste. methyl-5-pyrazolone or other 1-aryl-3-methyl-5- Applied to cellulose acetate fibres it gives a full pyrazolone. A particularly useful dyestuff is golden yellow colour, which shows excellent rep-hydroxybenzeneazo-1-pheny1-3-methyl-5-pysistance to discharge bythe usual reduction methrazolone. 1 ods. 5

The dyestufis of the invention exhibit a remarkable fastness to light and to the action of gg? i ig zzgggigggfi $igggzg reducing agents such as stannous chloride, which are commonly employed in the production of reparts f 3-methyl-4-hydroxy-l-aminobenare of great in the production of il1u mentioned Example 1, diazotization and Subseminated or coloured discharge effects. The dyequent coupling with phehylmethylpylazolohe stuffs, and particularly the unsulphonated membeing efiected as detailed in Example shade bers of the class, have a good aflinity for cellulose and Properties of the dyestuff are Very close to acetate and other organic derivatives of cellulose. those of the Product of Example 25 The term organic derivative of cellulose is intend- Eagample 3 T0 prepare p-hydroxybenzen ed to connote ethers and organic esters of celluw-3 m 5 lose, e. g. ethyl, methyl and benzyl cellulose and cellulose formate, propionate and butyrate. The preparation 15 effected as m Example 1 The dyestuffs may be produced by any suitable except that part? of 30 means for example by coupling a pymzolone pyrazolone are substituted for the 9 parts of pling component with a diazo compound containpheny1 methy1py raZ1ne there1 n used mg a hydroxy group in the para position to the Having described my invention what I desire diazo group. Para-hydroxy-benzene-azo-l-phento secure by Letters Patent 1S:

' yl-3-methyl-5-pyrazolone may be produced by i?g ggggg' gig 35 diazotising p-amino-phenol and coupling with 1pheny1-3-methyl-5py azolone. This dyestuff ,3 5??? igz ggg Elm-13013713 colours cellulose acetate in golden yellow shades e pyr and is very resistant to discharging agents. Simjfi iififig ggggiggg 1 'phenyL ilar valuable dyestuffs may be obtained from other 40 40 p-hydroxy-amines of the benzene series, for eX- A pyrazolone azo dye of the formula ample 3-methyl-4-hydroxy-l-amino-benzene, and E from other 1-aryl-3-methyl-5-pyrazolones of the C-NH\ Y Y benzene series, for example l-p-tolyl-3-methyl-5- X X NOY pyrazolone and l-o-methoxyphenyl-3-methyl-5- OHN=NOHCO/ Y Y 45 pyrazolone. X X

The following examples illustrate the invenwherein one X represents hydrogen or methyl and the others represent hydrogen, and one Y Emmple prepare p'hydmxybenzene'azo represents hydrogen, methyl or methoxy and the 50 1Imam/1'3'methyl'5pymzolone others represent hydrogen.

5.5 parts of p-aminophenol are dissolved in GEORGE HOLLAND ELLIS. 

